568 FETCH : 



while in a sixth case, they were killed by an immersion of six 

 hours forty-five minutes, but as the experiment was only 

 carried on for another transfer (at seven hours) this result is 

 doubtful. Transfers of mycehum plus spores were killed in 

 one case between two hours twenty minutes and four hours 

 forty-four minutes, but in the subsequent experiment to 

 determine a more approximate death point they survived an 

 immersion of seven hours. 



No agreement was expected between the results obtained by 

 the three methods, and it is clear that the results of the third 

 method depend upon the size of the masses of mycelium 

 transferred. For example, after twenty-four hours' immersion 

 in 1 per cent, carbolic acid all transfers of small fragments of 

 mycelium failed to grow, but growth was obtained from a 

 larger mass in the same solution. But there does not seem to 

 be any explanation of the variation in the results obtained by 

 transferring the spores alone, except on the supposition that the 

 spores vary in their power of resistance to the fungicide. The 

 spores are comparatively large, and are easily wetted by the 

 liquid. Examination of the hanging drops showed that in 

 no case did groups of spores enclose air bubbles, and tests of 

 the loop transfers gave the same result ; it is improbable, 

 tlierefore, that tlie variation is due to this cause. 



Copper Sulphate. 

 (1) A flask culture, six days old, was divided into two parts, 

 one of which was torn up in 1 per cent, carbolic acid, and 

 the other in 1 per cent, copper sulphate. The two bottles 

 containing the mixtures were then placed under an air pump, 

 and auy air in the mycelium extracted. Transfers were made 

 to flasks of sugar cane extract every twenty-four hours for 

 thirty-five days. No growth was obtained in any of the 

 transfers from carboHc acid. In the case of the copper 

 sulphate, good growth resulted in all transfers up to the 

 nineteenth ; the twentieth, twenty-first, and twenty-fourth 

 failed, but the subsequent transfers grew up to the twenty- 

 seventh ; no growth was obtained from the twenty -eighth and 

 seven following transfers. Germination was delayed about 

 two days in the last living transfers. Judged by this experi- 

 ment the killing power of copper sulphate is small compared 



